NFS, its applications and future
Brian Pawlowski
Vice President and Chief Architect beepy@netapp.com
NFS: Its applications and future - LISA „04
Who am I? Why am I here?
NFS: Its applications and future - LISA „04
The arc of the presentation
• • • • • • • • What is NFS? The evolution of NFS NFS Version 4 Drill down: Linux NFS Version 4 What about iSCSI? Linux compute clusters NFS in context Challenges for NFS
With occasional sidetracks…
NFS: Its applications and future - LISA „04
What is NFS?
NFS: Its applications and future - LISA „04
What is NFS?
• NFS is a protocol for a distributed filesystem.
– Based on Sun's RPC version 2 protocol – Can export arbitrary local disk formats
• First revision, NFSv2, was published in 1985.
– It exports basic POSIX 32-bit filesystems – Slow, particularly for writing files
• NFSv3, was published in 1994
– Extended to 64-bit files & improved write caching – It is perhaps the most commonly used protocol for sharing files on *NIX/Linux LANs today
NFS: Its applications and future - LISA „04
Remember these file systems?
• • • • Apollo Domain AT&T Remote File System (RFS) Andrew File System (AFS) Distributed File System (DFS) (NFS Version 4 is influenced by AFS)
NFS: Its applications and future - LISA „04
NFS Today
• “It was 20 years ago today.”
– SCSI and NFS grew up together
• Transformed from something you turn on in a UNIX release to a well-defined storage segment • Home directories • Large partitionable tasks that may run as parallel threads
– Typical applications include search engines, e-mail, animation and rendering, scientific simulations, and engineering
• Scalable databases • GRID computing
NFS: Its applications and future - LISA „04
NFS Version 4
NFS: Its applications and future - LISA „04
NFS Version 4
• Openly specified distributed filesystem
– NFSv2/v3 quasi-open with Informational RFC – Windows, AFS, DFS not “open”
• Well-suited for complex WAN deployment and firewalled architectures
– Reduced latency, public key security
• Strong security
– Public and Private key – Fine-grained access control
• Improved multi-platform support • Extensible
– Lays groundwork for migration/replication and global naming
NFS: Its applications and future - LISA „04
The IETF process and NFS
1998 Sun/IETF Agreement
BOF, working group forms
Strawman Proposal from Sun 1999
Meetings, writing, e-mail Prototyping by 5 organizations
Working Group Draft
Additional prototyping Six working group drafts Working Group Last Call IETF Last Call IESG Review Assign RFC number
2000 2001
Proposed Standard RFC 3010 Proposed Standard RFC 3530
Two independent implementations 6+ months
2002
NFS: Its applications and future - LISA „04
Draft Standard Internet Standard apotheosis
Couple things we did right this time
• Open source reference implementations of NFS Version 4 were funded early (started by Sun) • Interoperability events held 3 times a year
– With focus of non-Connectathon events on NFS Version 4
• Huge improvements in execution and coordination over NFS Version 3
NFS: Its applications and future - LISA „04
NFS Protocol Stack
NFSv4 (RFC3530)
KerberosV5 (RFC1510) SPKM-3 LIPKEY (RFC2847) RPC (RFC1831) XDR (RFC1832) RPCSEC_GSS (RFC2203) TCP*
NFS: Its applications and future - LISA „04
NFS Version 4 operations
• • • • • • • • • • • • • • • • • • • ACCESS CLOSE COMMIT CREATE DELEGPURGE DELEGRETURN GETATTR GETFH LINK LOCK LOCKT LOCKU LOOKUP LOOKUPP NVERIFY OPEN OPENATTR OPEN_CONFIRM OPEN_DOWNGRADE • • • • • • • • • • • • • • • • PUTFH PUTPUBFH PUTROOTFH READ READDIR READLINK RENAME RESTOREFH SAVEFH SECINFO SETATTR SETCLIENTID SETCLIENTID_CONFIRM VERIFY WRITE RELEASE_LOCKOWNER
NFS: Its applications and future - LISA „04
NFS operation aggregation
• The COMPOUND operation
– NFS procedures are now groupable
• Potential for reduced latencies and roundtrip times • Part of framework for minor versioning
NFS: Its applications and future - LISA „04
Example: mount server:/test/dir
• Client generates this COMPOUND
PUTROOFH GETFH LOOKUP(test) GETFH GETATTR
SYMLINK_SUPPORT LINK_SUPPORT FH_EXPIRE_TYPE TYPE SUPPORTED_ATTRS FSID
The operation formerly known as MOUNT
SECINFO (dir) LOOKUP (dir) GETFH GETATTR
NFS: Its applications and future - LISA „04
NFS Version 4 is secure
• Mandatory to implement
– – – – Optional to use Extensible via GSSAPI RPC Kerberos V5 available now Public key flavor emerging
• Security negotiated
– Per file system policy – Continuous security – Security negotiation mechanisms
• Levels
– Authentication – Integrity – Privacy
• ACLs (based on Windows NT)
NFS: Its applications and future - LISA „04
Specification vs. implementation
• RFC 3530 defines required, recommended and optional features
– The required features form core of interoperability – Recommended and optional features are negotiated
• ACLs, for example, are a “recommended” attribute
– Not required for compliance – Dependent on underlying local file system support on server (on Linux - that‟s a lot of file systems) – ACLs are ill-defined in *ix environs - mapping issues are tripping us up
NFS: Its applications and future - LISA „04
NFSv4 - Stateful
• Protocol is “session” oriented (OPEN call exists)
– But in reality NFS Version 3 was also stateful via adjunct Locking Protocol
• Lease-based recovery of state (simplified error handling) • File locking integrated into protocol
– OPEN provides atomicity for Windows integration
• Addition of delegations
– Client in absence of sharing allowed to locally cache data and locking state – This does not mean data sharing is defined in absence of explicit locking
NFS: Its applications and future - LISA „04
Delegations (making lemonade)
• Use stateful design to enhance performance and scalability • Enables aggressive caching on client
– Shared read – Write exclusive
• Reduced roundtrips of the wire
– Read, write, locking etc. cacheable locally – The fastest packet is the one never sent
• Server-based policy
– Server manages conflicts – Sharing model reverts to NFS Version 3 when conflicted
NFS: Its applications and future - LISA „04
The Pseudo file system
Server Local FS
Pseudofs
/
/ A A B C C F I G
D D
E F
H
I
NFS: Its applications and future - LISA „04
Protocol vs. Implementation II
• Administration amongst the remaining *ixes differ • Recommended and optional features require negotiation
– Security – Extensions
NFS: Its applications and future - LISA „04
Simplified server namespace
• Exported file systems mountable from a single server root
– Root filehandle for the top of the file tree – Still a client mount command
• For all shared/exported filesystems, server constructs pseudo filesystems to span name space • Client can still individually mount portions of the name space • Differing security policies can cover different parts of exported space
NFS: Its applications and future - LISA „04
Firewall friendly
PORTMAP MOUNT NFSv2/v3 LOCK/NLM STATUS
Port 111 Dynamic Port 2049 Dynamic Dynamic Dynamic
ACL*
}
NFSv4
Port 2049
TCP
NFS: Its applications and future - LISA „04
NFS Version 4 availability
• Network Appliance (Feb. „03), Hummingbird (late „02), Linux (via SuSE mid-‟04), in RedHat Fedora (May „04), RHEL 4.0 Dec. 04)
– Must be explicitly enabled
• Solaris 10 imminent (uh, yesterday)
– On by default
• IBM AIX 5L V5.3 • BSD (Darwin) (date?)
NFS: Its applications and future - LISA „04
The future of NFS Version 4
• • • • Enhanced “Sessions” based NFS (correctness) CCM - session-based security for IPsec Directory delegations Migration/replication completion
– Core protocol defines client/server failover behaviour – Definition of the server-server file system movement – Transparent reconfiguration from client viewpoint
• Proxy NFS file services (NFS caches) • Uniform global name space
– Features exist in the core protocol to support this
• Support for multi-realm security
NFS: Its applications and future - LISA „04
Scalability: Attacking the I/O bottleneck
• Remote Direct Memory Access
– Bypasses CPU on client and server for networking – Reduces the memory bottlenecks on high speed networks such as Infiniband or 10G ethernet.
– See the NFSv4.1 RDMA extensions
• Parallel storage extensions (pNFS)
– “Intelligent” clients are given (limited!) direct access to the storage net using block protocols such as iSCSI etc. – Bypasses server altogether for block file operations, but not for metadata
NFS: Its applications and future - LISA „04
Drill down: Linux NFS
NFS: Its applications and future - LISA „04
Linux 2.6 – Recent NFS (3 and 4) client changes
• Support for O_EXCL file creation • Cached ACCESS permission checks • “Intents” allow unnecessary lookups and permissions checks to be optimized away • Asynchronous read/write improvements
– Removed 256 page read/write request limit – Async support also for r/wsize < PAGE_SIZE
• DIRECT_IO / uncached I/O • RPCSEC_GSS
NFS: Its applications and future - LISA „04
Linux 2.6 NFS Version 4
• Framework added October „02 to Linux 2.5 • Additional cleanups and features added over past year
– Performance work to get to V3 levels
• Delegations
– Framework for atomic OPEN – Memory management issues – Basic state management
• State recovery
– Bug fixes and code stabilization
NFS: Its applications and future - LISA „04
Linux 2.6 NFS Version 4
• Goal is to stabilize basic V4 and add further advanced features
– Will remain an EXPERIMENTAL feature dependent on testing – No NFS V4 ROOT (for diskless operation)
• Must address the user experience
– State recovery under network partition – NFSv4 perceived as complicated to administer
• Strong security, names spaces, migration/replication, etc.
NFS: Its applications and future - LISA „04
Linux-2.6 – Generic server changes
• Adds upcall mechanism
– Adds RPCSEC_GSS support (version 3 and 4) – Id mapper – Improves support for exports to NIS or DNS domains.
• Zero-copy NIC support
– Accelerates NFS READ calls over UDP+TCP
• 32K r/wsize support
NFS: Its applications and future - LISA „04
Linux 2.6.10 NFS V4 - What‟s in
• All NFS ops and COMPOUND • GSSAPI
– LIPKEY/SPKM and Kerberos (authentication and integrity)
• Single server mount • Locking • Client side delegations (read and write)
– Does not cache byte-range locks
• ID mapping (UID to names - user@domain) • O_DIRECT bug fixes • AutoFS support
NFS: Its applications and future - LISA „04
Linux 2.6.10 NFS V4 - TODO
• Security
– RPCSEC_GSS privacy support – SECINFO – Keyrings
• Server side delegation support (going in now) • Migration/replication client support
– “Nohide” mount point crossing - RFC 3530 compliance
• ACL support • Named attribute support • Non-Posix server support (missing attribute simulation) • Volatile file handle handling • Global name space
NFS: Its applications and future - LISA „04
What about iSCSI?
NFS: Its applications and future - LISA „04
iSCSI background
SCSI Protocol
iSCSI
TCP IP
FCP FibreChannel
Parallel Bus
TCP/IP Transport for SCSI command sets SCSI block protocol access Internet standard - RFC 3720 iSCSI is a direct replacement for FCP FCP is the SAN fabric today
NFS: Its applications and future - LISA „04
The important thing about iSCSI is SCSI
The important stuff and common with FCP
// Ethernet Header IP
Checksum
TCP
iSCSI
SCSI Data…
CRC
Addressing and routing and security
NFS: Its applications and future - LISA „04
“So, iSCSI is a replacement for NFS, right?”
• In the first iSCSI presentation I made to a prospect, this was first thing out IT manager‟s mouth • I used to say “No”, but the thoughts underlying the question are interesting
NFS: Its applications and future - LISA „04
iSCSI value proposition
• Leverage existing Gigabit 10 Gigabit networking infrastructure • Leverage existing rich set of management tools • Leverage existing base of skilled personnel Reducing costs
NFS: Its applications and future - LISA „04
iSCSI points
• iSCSI software drivers freely and ubiquitously available
– Windows platforms – Linux, and other *ixes
• HBAs and TOEs
– Scale performance from software solution HW assist full offload
• Saying “performance” and “iSCSI” in the same breath though misses the point
– Performance is not always the primary issue (else use FC SAN) – Many application deployments have spare (CPU and I/O) capacity – Optimize performance as needed
NFS: Its applications and future - LISA „04
For some, iSCSI represents the path of least resistance
• It is semantically equivalent to FC SAN (SCSI)
– But more familiar because of TCP/IP and Ethernet - so friendly outside the data center
• Application migration is trivial
– My remote booting desktop from FC to iSCSI
• Provides a path for easily reclaiming FC port capacity by moving less critical apps to iSCSI • With some of the important cost benefits of NAS
NFS: Its applications and future - LISA „04
iSCSI is part of a solution
• Cost effective alternative to captured storage • Windows HCL afterburner • A place to move “less critical” SAN applications freeing up FC capacity
– The early adopter approach
• Friendly outside the data center
– And manageable!
• Easily envision applications like remote C: drive
– Remind me to tell you a story
• An additional tool in the storage toolbox
NFS: Its applications and future - LISA „04
Cluster computing and Linux
NFS: Its applications and future - LISA „04
The Old Way
Imagine Charlton Heston in a chariot.
NFS: Its applications and future - LISA „04
The New Way
Imagine an airplane full of chickens.
NFS: Its applications and future - LISA „04
“The GRID” – what is it?
• Sets of toolkits or technologies to construct pools of shared computing resources
– Screen-savers that use millions of desktop machines to analyse radio telescope data. – Vertical applications in the enterprise on a large Linux cluster. – Middleware that ties together geographically separated computing centres to satisfy the exponentially increasing demands of scientific research.
• To many, “Grid computing” and “Cluster computing” are synonymous.
NFS: Its applications and future - LISA „04
Modern numerology (this is not important)
86 2 128 2000 10000 <9 1 10? The preferred architecture for commodity computing (and oddly, the number of years it took the Red Sox to win the World Series) Number of physical processors in commodity pizza boxes (poor man‟s blade) Maximum expected nodes in a Linux database cluster Typical number of Linux nodes in a render or ECAD simulation farm today Expected number of nodes in Linux compute cluster in next two years?
Number of filers per 1000 Linux nodes in GRID
There is only one - Linus Torvalds The number of trusted minions to Linus
NFS: Its applications and future - LISA „04
Scalable compute cluster
• Linux is ahead of the game
– growing infrastructure, expertise and support
• It's all about choice! • No! It‟s all about freedom! • Well, no actually, it‟s all about cost.
NFS: Its applications and future - LISA „04
The rise of the Linux compute cluster
• Driven by cost • Particularly the cost of cheap commodity CPUs
– Monolithic application servers have no chance competing with the Tflop/price ratio
• Choices exist
– *BSD development marches on – Sun is renewing its investment in Solaris x86 – Even Windows has a market share
NFS: Its applications and future - LISA „04
Compute cluster points
• The x86 platform won
– Any questions?
• Support costs may still be significant
– ...but largely offset by the hardware cost savings - it‟s about leveraging small MP commodity x86 hardware – Some customers choose to pay more for better quality in order to lower support costs and improve performance – Maturation of “free software” - paying for support
• For Unix environments, NFS is the cluster file sharing protocol of choice
– Customers simply want storage solutions that scale as easily as their compute clusters
NFS: Its applications and future - LISA „04
Applications: Batching
• Large partitionable tasks that may run as parallel threads
– Clusters may include up to several thousand nodes – Often uses LSF and other queueing tools to manage jobs – Read-only data may be shared, but writing is partitioned to avoid locking issues. – Typical applications include search engines, email, animation and rendering, scientific simulations, and engineering
NFS: Its applications and future - LISA „04
Other applications
• Scalable databases
– Fewer nodes than the batch case: up to a hundred or so. – High degree of write sharing necessitates heavier use of locking – Data integrity is often supported by specialized fencing and recovery techniques that may again need support in the underlying filesystem.
• Extremely I/O intensive high performance computing • GRID computing
NFS: Its applications and future - LISA „04
Cluster-friendly features in NFSv4
• Stateful model
– ...but recovery remains client driven! – in case of a recoverable server outage, clients just retry operations until they succeed
• Leases solve NFS Version 3 state leakage problems due to client outages
– Cures the “lost locks” syndrome – But introduces new issues on network partition
• Delegations allow for aggressive caching
– Stops short of a full coherency model, though – Callback mechanism is firewall-unfriendly.
NFS: Its applications and future - LISA „04
Cluster-friendly features in NFSv4
• GRID friendly
– Obligatory support for strong security makes NFS deployment over the internet possible
• Including public key • Includes support for data encryption
• Firewall-friendly: only port 2049 needs to be opened
• there are no side-band mount/lock/... protocols • callbacks/delegations are not mandatory
NFS: Its applications and future - LISA „04
NFS in the short term future
• Aim to provide robust global name spaces • Adaptations to work with GRIDs
– GRIDNFS – project to adapt NFS to the Globus GRID toolkit – In the long run, we need improved caching models for use with high latency environments
• Performance improvements using hardware assisted networking
– NFSv4.1 includes support for RDMA
NFS: Its applications and future - LISA „04
Storage in a clustered environment
• “Scale my storage as easily as I can scale my CPUs.” • Data sharing
– Data must be accessible to all compute nodes
• (high) data availability
– No single point of failure
• Reliable data handling
– No data corruption
• Security
– In particular secure transport of data between compute and storage nodes
• Support commodity TCP/IP and ethernet networking • Performance
NFS: Its applications and future - LISA „04
Scaling yet further
• Virtualization techniques permit horizontal scaling of storage using the current protocol
– See NetApp/Spinnaker
• Parallel NFS – NFSv4 extensions to scale beyond storage network bandwidth limits
– Allow for striping files across several storage units – Explore SAN and object storage integration (NFSv4 as metadata server)
NFS: Its applications and future - LISA „04
Putting NFS in perspective
NFS: Its applications and future - LISA „04
Let‟s put this in perspective
• “Wow. Michaelangelo, great statue - was that a 7 inch chisel you used?” • “Great flick Welles, what camera did you use?” • “Great quarter you guys had! Did you use NFS to access your financial data?”
NFS: Its applications and future - LISA „04
It‟s about applications
• Applications drive storage choices
– What does the application vendor support? – What do they recommend? – For example, Exchange is driving iSCSI in the Windows environment
• Mix of applications in a single enterprise
– There is no one perfect storage approach – There‟s likely more than one vendor
NFS: Its applications and future - LISA „04
It‟s about data management
• Integration of applications with data management
– Key applications like Exchange - applicationdriven backup/restore – Fertile ground for virtualization - blurring line between client application and storage
• Disaster recovery • Finding data when you need it
– Higher level data organization and grouping?
NFS: Its applications and future - LISA „04
Non Disruptive Migration
Migration:
Global Name Space
NearStore
Fast (on-demand) Transparent to users Migration of Name Space or backend Volumes Migrate aged data to NearStore
Vol A Vol B
Vol B
Vol C
Vol B
NFS: Its applications and future - LISA „04
It‟s about cost
• Ability to (re)provision, expand and manage storage to maintain high utilization will most affect overall cost long term • Leveraging commodity networking
– iSCSI and NFS are similar here
• Primary storage and Nearline support for all storage access - transparently
– Migration and replication
• Consolidation to reduce management costs
NFS: Its applications and future - LISA „04
Existing Storage Hierarchy
Primary Storage
Servers
Price/Performance Gap
Archive Targets
Optical Library
Storage Network
LAN or WAN
Storage Network
Heterogeneous Storage
Tape Library Filers
$$$$$/ MB
Very Fast
$/ MB Slow
• The traditional two-tier hierarchy creates a large price/performance gap • Current challenges need a storage solution that fills the gap
NFS: Its applications and future - LISA „04
Economics of recovery
• Acceptable downtime is application dependent • Simplest – but most costly - approach is full mirror online • ATA drives are cheap
NFS: Its applications and future - LISA „04
Emerging Storage Hierarchy
Primary Storage
Servers
Backup Target/ Reference Data
Archive Targets
Optical Library
LAN or WAN
Storage Network
Storage Network
Heterogeneous Storage
Tape Library Filers
$$$$$/ MB Very Fast
NearStoreTM Appliance $$/MB Fast
$/ MB Slow
NFS: Its applications and future - LISA „04
Understanding the context around NFS
• Regardless of data access protocol, similar issues and solutions in data management
– Common management regardless of access method
• That other operating systems (besides Linux) drive fundamental architecture decisions
– Blade provisioning via NFS is a non-starter perhaps because of multi-OS support – Enter iSCSI - the least common denominator - the Windows splash effect
• People don‟t buy NFS servers
– They buy Oracle or other applications – They build application compute clusters – And manage the data around it - with NFS perhaps
NFS: Its applications and future - LISA „04
beepy, are you saying there is no difference between storage architectures?
NFS: Its applications and future - LISA „04
Differences are important
• NAS protocols define a file view - higher level organization and semantics
– Enables sharing – Enables large compute clusters (>5,000 nodes)
• iSCSI, like FC SANs, provides simpler SCSI block interface
– Higher level semantics via explicit file system encapsulation – Sharing via layered cluster file system (complexity and cost?)
• Customers will use and continue to explore a variety of approaches
NFS: Its applications and future - LISA „04
The challenge for NFS
NFS: Its applications and future - LISA „04
Other than that Mrs. Lincoln…
• NFS = Network File System • NFS = Not For Speed • NFS = Not For Security But an NFS vendor may sit there and think “My side of the boat is dry!” Exactly.
First impressions last a long time, and hard to turnaround once set.
NFS: Its applications and future - LISA „04
So, back to NFS - what do customers want?
• No surprises
– Customers really want a better NFS Version 3 – Are we prepared to provide support for NFS Version 4?
• Reliability
– Testing – Scalability
• Playing well with others
– Agreeing on common administration models – Agreeing on common features (else we will drop things from spec in IETF)
• Security
– Administration needs to be simplified simplified simplified
• Performance is at bottom of list I think
NFS: Its applications and future - LISA „04
Additional Resources
• NFS
– http://www.netapp.com/tech_library/ftp/3183.pdf (Linux NFS) – http://www.netapp.com/tech_library/hitz94.html (NFS Version 3) – http://www.beepy.com/SANEnfs.pdf (NFS and Linux clusters)
• NFS Version 4
– – – – http://www.ietf.org/rfc/rfc3530.txt http://www.nluug.nl/events/sane2000/papers/pawlowski.pdf (OLD) http://www.redbooks.ibm.com/abstracts/SG247204.html http://www.nfsv4.org
• SAN and iSCSI case studies
– http://www.netapp.com/case_studies/index_prod.html#san-nas
• SAN Performance Technical Report
– http://www.netapp.com/tech_library/3321.html
NFS: Its applications and future - LISA „04
Questions
NFS: Its applications and future - LISA „04